CARDIOVASCULAR SYMPATHOINHIBITORY NEURONS FORM AN EXTENDED LONGITUDINAL COLUMN IN CAT LATERAL MEDULLA

A search for vasomotor depressor sites in the lateral medullary brainstem of anesthetized cat using microinjections of AMPA has delineated a longitudinal column of sympathoinhibitory neurons consisting of the rostral depressor area, the caudal ventrolateral medulla, and a new intermediate depressor area. Systematic blockade of these three subregions with bilateral microinjections of kynurenic acid indicates a uniform involvement of the entire column with sympathetic baroreflex, but a slightly greater involvement of the anterior portion, over the posterior, with regulation of cardiovascular tone.